The present technology relates to an imaging device, an imaging method, and an electronic device, and particularly to an imaging device, an imaging method, and an electronic device that can obtain a signal with an excellent S/N and with a wide dynamic range.
In related art, the PD (photodiode) of each pixel in a solid-state imaging device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor generates a charge according to light received by the PD. Many solid-state imaging devices are configured such that the charge of a PD is transferred to an FD (Floating Diffusion) and the signal of a voltage corresponding to the charge generated in the PD is extracted by measuring the potential of the FD.
In such a solid-state imaging device, when the FD has a low capacitance, a gain at a time of conversion of the charge into the voltage by the FD is increased, and noise included in the signal output from the pixel is relatively reduced, thus resulting in a better S/N (signal-to-noise ratio) of an image signal. However, the FD of the low capacitance reduces an amount of charge that can be handled in the pixel, and narrows the dynamic range of the image signal, for example.
On the other hand, when the FD has a high capacitance, the amount of charge that can be handled in the pixel is increased, and for example the dynamic range of the image signal can be widened. However, the FD of the high capacitance decreases the gain at the time of conversion of the charge into the voltage by the FD, and the noise is also amplified when the image signal is amplified in a circuit in a subsequent stage, thus resulting in a degradation in S/N of the image signal.
There is accordingly a desire for a solid-state imaging device that can obtain an image signal with an excellent S/N and with a wide dynamic range. Japanese Patent Laid-Open No. 2009-505498 (hereinafter referred to as Patent Document 1), for example, proposes a solid-state imaging element in which an FD is formed by two capacitances, and a signal measured by one capacitance is used when there is a small amount of charge generated by a PD and a signal measured by the two capacitances is used when there is a large amount of charge generated by the PD.